﻿using System.Data;
using System.IO;
using System.Linq;
using System.Text;

namespace Xwltz.Framework.Helper
{
    public class CsvFileHelper
    {
        /// <summary>
        /// 将DataTable中数据写入到CSV文件中
        /// </summary>
        /// <param name="dt">提供保存数据的DataTable</param>
        /// <param name="fullPath">CSV的文件路径</param>
        public static void SaveCsv(DataTable dt, string fullPath)
        {
            var fi = new FileInfo(fullPath);
            if (fi.Directory != null && !fi.Directory.Exists)
            {
                fi.Directory.Create();
            }
            var fs = new FileStream(fullPath, FileMode.Create, FileAccess.Write);
            //StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);
            var sw = new StreamWriter(fs, Encoding.UTF8);
            var data = "";
            //写出列名称
            for (var i = 0; i < dt.Columns.Count; i++)
            {
                data += dt.Columns[i].ColumnName;
                if (i < dt.Columns.Count - 1)
                {
                    data += ",";
                }
            }
            sw.WriteLine(data);
            //写出各行数据
            for (var i = 0; i < dt.Rows.Count; i++)
            {
                data = "";
                for (var j = 0; j < dt.Columns.Count; j++)
                {
                    var str = dt.Rows[i][j].ToString();
                    str = str.Replace("\"", "\"\"");//替换英文冒号 英文冒号需要换成两个冒号
                    if (str.Contains(',') || str.Contains('"')
                        || str.Contains('\r') || str.Contains('\n')) //含逗号 冒号 换行符的需要放到引号中
                    {
                        str = $"\"{str}\"";
                    }

                    data += str;
                    if (j < dt.Columns.Count - 1)
                    {
                        data += ",";
                    }
                }
                sw.WriteLine(data);
            }
            sw.Close();
            fs.Close();
        }

        /// <summary>
        /// 将CSV文件的数据读取到DataTable中
        /// </summary>
        /// <param name="filePath">CSV文件路径</param>
        /// <returns>返回读取了CSV数据的DataTable</returns>
        public static DataTable OpenCsv(string filePath)
        {

            //Encoding encoding = Common.GetType(filePath);
            var dt = new DataTable();
            var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);

            //StreamReader sr = new StreamReader(fs, Encoding.UTF8);
            var sr = new StreamReader(fs, Encoding.UTF8);
            //string fileContent = sr.ReadToEnd();
            //encoding = sr.CurrentEncoding;
            //记录每次读取的一行记录
            string strLine;
            //记录每行记录中的各字段内容
            string[] aryLine = null;
            string[] tableHead = null;
            //标示列数
            var columnCount = 0;
            //标示是否是读取的第一行
            var isFirst = true;
            //逐行读取CSV中的数据
            while ((strLine = sr.ReadLine()) != null)
            {
                //strLine = Common.ConvertStringUTF8(strLine, encoding);
                //strLine = Common.ConvertStringUTF8(strLine);

                if (isFirst)
                {
                    tableHead = strLine.Split(',');
                    isFirst = false;
                    columnCount = tableHead.Length;
                    //创建列
                    for (var i = 0; i < columnCount; i++)
                    {
                        var dc = new DataColumn(tableHead[i]);
                        dt.Columns.Add(dc);
                    }
                }
                else
                {
                    aryLine = strLine.Split(',');
                    var dr = dt.NewRow();
                    for (var j = 0; j < columnCount; j++)
                    {
                        dr[j] = aryLine[j];
                    }
                    dt.Rows.Add(dr);
                }
            }
            if (aryLine != null && aryLine.Length > 0)
            {
                dt.DefaultView.Sort = tableHead[0] + " " + "asc";
            }

            sr.Close();
            fs.Close();
            return dt;
        }
    }
}
